COLLAPSE OF INTEGER HALL GAPS IN A 2-DIMENSIONAL HOLE SYSTEM

In the integral quantum Hall regime, Wigner crystallization due to the Landau-level mixing is investigated in a two-dimensional hole system. By calculations of excitation energies, we show that Landau-level mix ing effects can destroy the energy gap, which leads to an integral qua ntum Ball effect, at finite wave vector. Such a destruction of the ene rgy gap at finite wave vector is interpreted as Wigner crystallization in a two-dimensional hole system.